To obtain a flow rate measurement control apparatus which can measure, control a flow rate with a very small pressure loss and quick response performance without changing an arrangement relationship of other mechanisms and characteristics of a flow in a set flow path.

In a flow path having a certain characteristic in relationship of a pressure and a flow rate, a variable sectional are orifice 12 is formed of an orifice plate 3 with a fixed orifice 4 of a constant maximum diameter and a variable core 8 which smoothly changes a sectional area thereof along a center axis 5 and is movable linearly. A linear driving mechanism (linear actuator) 20 is arranged at a fixed core 7 supporting the movable core 8 in the linearly movable manner, so that a movement position of the movable core 8 is correctly controlled. The orifice of a variable sectional area is constituted as a function of the movement position of the movable core 8. A resistance of the flow path is reduced. Therefore, the flow rate can be measured and controlled correctly in a wide flow rate range with high-speed response performance.